In the related art, there is a known light-source device that uses a plurality of solid-state light sources such as LEDs (light emitting diodes) that emit monochromatic light beams and that generate a white illumination light beam by multiplexing red, green, and blue monochromatic light beams (for example, see Patent Literatures 1 to 3).
The green light beam emitted by the green LED has a lower light level as compared with the red light beam and the blue light beam emitted by the red LED and the blue LED, respectively, and, furthermore, the peak wavelength thereof is skewed toward the short-wavelength side of the green wavelength region. Therefore, in the spectrum of the generated illumination light beam, a truncated wavelength region is created between the peak wavelength of the green light beam and the peak wavelength of the red light beam, and thus, it is not possible to generate an illumination light beam having an ideal color temperature. Therefore, in Patent Literature 3, a white LED is used in addition to the red, green, and blue LEDs, and the color temperature of the illumination light beam is adjusted by correcting the spectrum of the green wavelength region by using a certain component of the white light beam emitted by the white LED.
In particular, in the case of a light-source device that is applied to a medical endoscope, in order to accurately observe and diagnose mucosa on the surface of an internal organ, which serves as an observation subject, by using an endoscope video image, the spectral characteristics of the green-to-red wavelength region are important. In other words, although the mucosa exhibits relatively high spectral reflectance in the green-to-red wavelength region, the spectral reflectance is not constant. Therefore, in order to accurately reproduce the tint of the mucosa in an endoscope video image, it is necessary to illuminate the mucosa with an illumination light beam having a good spectral characteristics with a low level spectral truncation in the green-to-red wavelength region.